Caster wheel arrangement with damping device

ABSTRACT

A CASTER WHEEL ARRANGEMENT IS PROVIDED WITH MEANS FOR DAMPING SHOCKS AND JARS WHEN OBSTACLES ARE ENCOUNTERED BY THE CASTER WHEEL WHEREBY THE STRUCTURE OF THE CASTER WHEEL ARRANGEMENT AS WELL AS THE LOAD CARRIED THEREBY IS PROTECTED FROM DAMAGE.

March 2, 1971 G. E. w. LEWIN CASTER WHEEL ARRANGEMENT WITH DAMPINGDEVICE Original Filed Nov. 20, .1967

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United States Patent Int. Cl. A47b 91/00 US. C]. 16-44 1 Claim ABSTRACTOF THE DISCLOSURE A caster wheel arrangement is provided with means fordamping shocks and jars when obstacles are encountered by the casterwheel whereby the structure of the caster wheel arrangement as well asthe load carried thereby is protected from damage.

This application is a divisional of my application, Ser. No. 684,160,filed Nov. 20, 1967.

According to the present invention a damping device is provided for acaster wheel arrangement, in which the Wheel fork has no rivet but alarge open central space.

It was found in practice that the wheel axis and other elements in acaster wheel arrangement can be easily damaged by hard and sudden bumpsagainst the wheel, for example when the Wheel under heavy load collideswith an obstacle. For reducing the damaging effect of such impacts,attempts have been made to damp the impacts by making the caster wheelto some extent resilient. According to conventional constructions,tension springs or compression springs have been employed which by meansof projecting links damp the effect of an impact against the wheel. Noneof these constructions, however, has proved successful. The reason isprimarily found in the difliculty of building the springs into theconstruction without making it clumsy and diflicult to handle. Moreover,the conventional constructions are very expensive and have been usedonly to a very limited extent.

This invention has as its object to eliminate the shortcomings of theconventional damper constructions for caster Wheels and substantially toimprove the damping effect of sudden shocks.

The caster wheel arrangement comprises a holder rigidly mounted on anobject, which holder is adapted to detachably retain a mounting platehaving a large central hole, in which hole a wheel fork with anoutwardly bent upper flange of a diameter exceeding that of the centralhole can be inserted from above and via bearing means to rest againstthe surface of the plate surrounding the central hole, as described inmy application 684,160. The wheel fork of the present inventionsubstantially comprises two parts, an upper forked part rotatablymounted in the mounting plate, and a lower L-shaped part, supporting thewheel, pivotally mounted in the upper forked part on a horizontal axis,the damping device being mounted in the forked part for damping themovements of the wheel caused by shocks.

FIG. 1 shows a side-view, partially in cross-section, of a caster wheelarrangement with a damping device accord ing to the invention.

FIG. 2 shows a horizontal cross-section through the arrangementaccording to FIG. 1 along the line IIII thereof.

The caster wheel arrangement, as described in my copending application684,160 filed Nov. 20, 1967 includes a mounting plate 1 which isdetachably and slidably retained by a holder securely mounted on anobject. The mounting plate 1 as shown in FIG. 1 has a relatively largecentral opening 49 into which the wheel fork 43 is inserted from above.The upper portion of the wheel fork is cylindrical and has an outwardlyextending flange 4 about its upper edge, which flange has a diametergreater than the diameter of the opening 49 so as to provide with thesurrounding edge 9 of the opening 49 a race for ball bearings 40. Asecond race for ball bearings 41 above the flange 4 may be provided, asshown, by employing a thrust plate 10.

As shown in the figures, the invention substantially comprises amounting plate 1 which is provided with a large" central hole 49 havinga horizontal edge portion, and a wheel fork 43 which via ball bearings40 and 41 is rotatably mounted within the central hole 49 of themounting plate. The wheel fork 43 comprises two parts, an upper forkedpart 42 having an upper substantially cylindrical shape which isrotatably mounted in the mounting plate 1, and a lower L-shaped part,45, 46, which is pivotally mounted in the upper part by a pivotal axis47 which is mounted horizontally in the lower portion of said forkedpart and may comprise two axle journals as seen in FIG. 2.

The L-shaped part 45, 46 is shaped as an angular lever with asubstantial right angle, so that one lever 45 of rectangular crosssection extends from the pivotal axis 47 vertically upwardly into theupper cylindrical part 42, and the other lever 46 which carries a casterwheel 48 extends horizontally outwardly from the pivotal axis 47.

According to FIG. 1 the damping device 44 comprises resilient dampingmembers, for example in the form of compression springs (not shown) orblocks of elastic material, mounted on opposed sides of the upper end ofthe rectangular vertical part 45 of the wheel fork as shown in FIGS. 1and 2 so as to resiliently restrict movement of upper part 42 about axis47.

According to the embodiment shown in FIG. 2, the damping device is anelastic mass which entirely surrounds the upper rectangular end of thevertical part 45 of the wheel fork.

When compression springs are used, the springs are disposed on opposedsides of part 45 so that their axes ex tend transversely of the axis ofpivotal axis 47 thus restraining movement of the wheel fork 45, 46 aboutthe axis 47.

According to a further embodiment (not shown), the entire upperrectangular part 45 of the wheel forkmay be embedded in an elastic masswhich also fills the central opening in part 45.

When the last mentioned embodiment is employed, metallic sounds whichpossibly may arise due to metalmetal contact, for example in thebearings or in other place, are eliminated and the caster wheel runsentirely noiselessly, while at the same time providing a good dampingeffect in all directions.

What distinguishes the present invention essentially over conventionaldamping constructions is, that the damping can be effected Within thecaster wheel arrangement, due to the construction of the latter.

It is obvious that the invention is not restricted to the embodimentsdescribed and shown, but can be utilized in other ways within the scopeof the claims.

I claim:

1. A damping device for a caster wheel arrangement comprising anon-rotatable mounting plate detachably mountable on an object, a wheelfork including a forked part and an upper cylindrical part defining ahollow space therein and mounted on said mounting plate to rotate abouta vertical axis, an L-shaped part pivotally mounted within said forkedpart about a horizontal axis, the upwardly extending arm of saidL-shaped part extending upwardly into the hollow space of said uppercylindrical part, a caster wheel mounted adjacent the outer end of thelower arm of said. L-shaped part, and resilient damping means disposedcircumferentially within said hollow space between the upper cylindricalpart of said wheel fork and the upper portion of the upwardly extendingarm of the L-shaped part of resilient damp movement of the L-shaped partabout its horizontal axis when the caster wheel strikes an obstacle.

4 References Cited UNITED STATES PATENTS 2/1930 Herold 16-44 1/ 1949Christensen 1644

